In UpdateWorker?.pm, _compare_and_act_on_config_changes does the following:
$self->_ensure_filename($service,
$old_data_source, $data_source,
$old_ds_config, $ds_config)
and $self->_ensure_tuning($service, $data_source,
$ds_config);
_ensure_filename() then checks whether it needs to update the filename, and does it if needed. It returns true (1) if it's updated the filename, false () if an error happened. The default return value if it should _not_ update the filename, is true (1). This means that _ensure_tuning is almost always run. This function in turn does no check to see if changes are needed, it just does three rrdtool tune commands on the rrd file (min, max, type).
These three extra operations spam the log quite a bit, as well as cause extra load on the munin server.
